The present invention relates generally to powered systems for opening and closing closures such as doors and hatches, and more particularly, to powered systems for opening and closing motor vehicle closures.
Motor vehicle liftgates and deck lids act to close and seal the rear cargo area of a motor vehicle. Typically, these closures or closure structures are mounted in a frame located at the rear of the vehicle, usually on a horizontally extending axis provided by a hinge. The liftgate is thus positioned to rotate between a closed position adjacent to the frame and an open position, in which the cargo area of the motor vehicle is accessible. The liftgate or deck lid itself is often very heavy, and because of its mounting, it must be moved against gravity in order to reach the open position. Because of the liftgate""s weight, it would be a great burden if a user was required to lift the liftgate into the open position and then manually hold it in place in order to access the vehicle""s cargo area.
In order to make it easier to open liftgates and deck lids, most modem motor vehicles use gas or spring-loaded cylindrical struts to assist the user in opening and holding open liftgates and deck lids. The struts typically provide enough force to take over the opening of the liftgate after the liftgate has been manually opened to a partially opened position at which the spring force and moment arm provided by the struts are sufficient to overcome the weight of the liftgate, and to then hold the liftgate in an open position.
Usually, a motor vehicle liftgate-assist system consists of two struts. The two struts in a typical liftgate assembly are each pivotally mounted at opposite ends thereof, one end pivotally mounted on the liftgate and the other end pivotally mounted on the frame or body of the motor vehicle. Each strut""s mounting point is fixed, and the strut thus possesses a fixed amount of mechanical advantage in facilitating the manual opening process. In addition, because the force provided by the struts is constant, the user must thrust downward on the liftgate and impart sufficient momentum to the liftgate to overcome the strut forces in order to close the liftgate.
Automated powered systems to open and close vehicle liftgates are known in the art. However, these systems typically use a power actuator to apply a force directly to the liftgate to enable opening and closing thereof. For example, U.S. Pat. No. 5,531,498 to Kowall discloses a typical liftgate-opening system in which the gas struts are actuated by a pair of cables which are, in turn, wound and unwound from a spool by an electric motor. Because this typical type of powered system acts as a direct replacement for the user-supplied force, it provides relatively little mechanical advantage from its mounted position, typically requires a significant amount of power to operate, and is usually large, requiring a significant amount of space in the tailgate area of the vehicle, which is undesirable.
Control systems for the typical powered liftgate systems are also available. Such control systems usually include at least some form of obstacle detection, to enable the liftgate to stop opening or closing if an obstacle is encountered. These obstacle detection systems are usually based on feedback control of either the force applied by the liftgate or actuator motor or the speed at which the liftgate or motor is moving. One such control system for the type of cable-driven liftgate actuator described above is disclosed in U.K. Patent Application No. GB 2307758A. In general, the control system of this reference is designed to control the movement of the liftgate based on the measured liftgate force, using an adaptive algorithm to xe2x80x9clearnxe2x80x9d the liftgate system""s force requirements. However, the movement of a liftgate is a complex, non-linear movement and existing control systems are usually adapted only for conventional xe2x80x9cbrute forcexe2x80x9d powered liftgate systems.
Other prior art power liftgate systems are more passive. For example, DE 198 10 315 A1 discloses an arrangement in which the angular position of a strut is changed in order to facilitate opening and closing of a deck lid. However, the structural configuration of the disclosed design is such that it permits a very limited range of closure movement and limited mechanical advantage in the different positions. In addition, among numerous other disadvantages, the device disclosed in DE 198 10 315 A1 does not provide a controlled system that enables dynamic control of the closure during movement thereof. This reference also does not contemplate use of the closure in manual mode, among other things.
DE 197 58 130 C2 proposes another system for automated closure of a deck lid. As with the ""315 reference, the ""130 reference does not contemplate or allow dynamic control over the deck lid, use of the deck lid in manual mode, and does not enable a power driven closing force to be applied to the lid. Moreover, both of the ""130 and ""315 references disclose very large structural arrangements, making packaging in a vehicle very difficult.
One aspect of the present invention relates to a powered closure drive mechanism for a vehicle. The powered closure drive mechanism includes a strut that is mountable between a frame of a vehicle and a closure pivotally connected to the frame. The strut has opposite ends moveable in opposite directions and is biased to move the opposite ends toward and away from one another. The angular orientation of the strut is adjustable between angular orientations in which the bias of the strut overcomes the weight of the closure so as to move the closure in a closure opening direction and angular orientations in which the weight of the closure overcomes the bias of the strut so as to move the closure in a closure closing direction. A motor assembly is operatively coupled with the strut so as to adjust the angular orientation of the strut and thereby effect opening and closing of the closure. A dynamic property detector is also included in the mechanism to detect a dynamic property of the closure. A controller is operably connected with the motor and the dynamic property detector. The motor adjusts the angular orientation of the strut based on information received from the dynamic property detector so as to maintain closure velocity within predetermined velocity limits.
In this aspect of the invention, the dynamic property detector may comprise, for example, an inclinometer carried by the closure, or an encoder operatively connected with the hinge on which the closure is mounted. More generally, the dynamic property detector may be any type of velocity detector. The mechanism may also include a strut orientation detector that sends a signal to the controller based on the orientation of the strut. The strut orientation detector may be, for example, a Hall Effect sensor operatively associated with the motor.
Another aspect of the invention relates to a powered closure drive mechanism for a vehicle. Using this mechanism, the strut assumes a first orientation when the closure is fully opened and a second orientation when the closure is fully closed. A pivot point of the strut is moved by the motor when effecting opening and closing movement of the closure and is disposed in a same manual mode position when the strut is in either of the first and second orientations, enabling manual opening and closing of the closure.
A further aspect of the present invention relates to a powered closure drive system mounted to the rearward-most pillar of a vehicle frame. A motor is operatively coupled with the strut so as to adjust the angular orientation of the strut and thereby facilitate opening and closing of the closure. An arm is connected to the motor and one end of the strut. A controller is operatively connected with the motor to control operation of the motor.
According to this aspect of the invention, the motor may be mounted within the rearward-most pillar so as to provide a shaft extending into the longitudinal channel for connection with the arm. Alternatively, the motor may provide a shaft extending into the longitudinal channel for connection with the arm. The system may also include a panel constructed and adapted to cover the motor. The panel would be disposed on an interior portion of the vehicle.
Yet another aspect of the invention relates to a powered closure drive system for a vehicle. Using this mechanism, the strut assumes a first orientation when the closure is fully opened and a second orientation when the closure is fully closed. When the closure approaches the fully closed position, the strut has an angular orientation such that a line of action of the strut causes a closing force to be applied to the closure.
Another aspect of the invention provides to a powered closure drive system for a vehicle. Using this mechanism, the strut assumes a first orientation when the closure is fully opened and a second orientation when the closure is fully closed. During a movement from the first orientation toward the second orientation, the motor is moved such that the second end of the strut is positioned outwardly of a line of action defined between a hinge pivot axis of the closure and the pivotal strut connection with the closure at the first end of the strut so as to apply a closing force to the closure.
According to this aspect of the invention, the powered closure drive system also includes an arm having a first connecting structure adapted for connection to the first end of the strut and a second connecting structure adapted for connection to the output shaft of the motor. Additionally, an inclination detector is mounted on the closure and is capable of detecting the inclination of the vehicle when the closure is closed. The inclination detector is connected with the controller to enable the motor to adjust the orientation of the strut based on the inclination of the strut, the vehicle, or the strut and the vehicle. According to this aspect, the inclination detector may also detect the inclination of the closure when the closure is moving.
An additional aspect of the invention relates to a rear vehicle assembly of a motor vehicle having a powered closure drive system.
Another aspect of the present invention relates to an automated, pivoted closure system.
An additional aspect of the invention relates to a method for controlling an automated, pivoted closure. The method comprises providing a fixed structure, a pivotal structure mounted for pivotal movement about a horizontal axis, and a biased strut connected between the fixed structure and the pivotal structure, measuring a dynamic property of a closure as it moves under the influence of the bias of the strut and the gravitational forces of its weight, and controlling a motor to change an angular orientation of a strut relative to the horizontal axis based upon a desired dynamic property of the closure so as to maintain the closure within a desired dynamic property profile. The dynamic property may be selected from the group consisting of closure position, closure velocity, closure acceleration.